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AtlanticFlamethrower

More Evidence Against The "hockey Stick"

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rcschronologiesrev2.gif

The red line represents a sample of 12 tree ring cores from the CRU Archive. The black line a sample of 34 - from the same region. The sample of 34 was not included in the archive.

Any warministas out there still plan to invest in cherry tree orchards?

Ross McKitrick:

September 27th, 2009 at 12:54 pm

Here's a re-cap of this saga that should make clear the stunning importance of what Steve has found. One point of terminology: a tree ring record from a site is called a chronology, and is made up of tree ring records from individual trees at that site. Multiple tree ring series are combined using standard statistical algorithms that involve detrending and averaging (these methods are not at issue in this thread). A good chronology–good enough for research that is–should have at least 10 trees in it, and typically has much more.

.

1. In a 1995 Nature paper by Briffa, Schweingruber et al., they reported that 1032 was the coldest year of the millennium - right in the middle of the Medieval Warm Period. But the reconstruction depended on 3 short tree ring cores from the Polar Urals whose dating was very problematic. http://www.climateaudit.org/?p=877.

2. In the 1990s, Schweingruber obtained new Polar Urals data with more securely-dated cores for the MWP. Neither Briffa nor Schweingruber published a new Polar Urals chronology using this data. An updated chronology with this data would have yielded a very different picture, namely a warm medieval era and no anomalous 20th century. Rather than using the updated Polar Urals series, Briffa calculated a new chronology from Yamal - one which had an enormous hockey stick shape. After its publication, in virtually every study, Hockey Team members dropped Polar Urals altogether and substituted Briffa's Yamal series in its place.

http://www.climateaudit.org/?p=528. PS: The exception to this pattern was Esper et al (Science) 2002, which used the combined Polar Urals data. But Esper refused to provide his data. Steve got it in 2006 after extensive quasi-litigation with Science (over 30 email requests and demands).

3. Subsequently, countless studies appeared from the Team that not only used the Yamal data in place of the Polar Urals, but where Yamal had a critical impact on the relative ranking of the 20th century versus the medieval era.

http://www.climateaudit.org/?p=3099

4. Meanwhile Briffa repeatedly refused to release the Yamal measurement data used inhis calculation despite multiple uses of this series at journals that claimed to require data archiving. E.g. http://www.climateaudit.org/?p=542

5. Then one day Briffa et al. published a paper in 2008 using the Yamal series, again without archiving it. However they published in a Phil Tran Royal Soc journal which has strict data sharing rules. Steve got on the case. http://www.climateaudit.org/?p=3266

6. A short time ago, with the help of the journal editors, the data was pried loose and appeared at the CRU web site. http://www.climateaudit.org/?p=7142

7. It turns out that the late 20th century in the Yamal series has only 10 tree ring chronologies after 1990 (5 after 1995), making it too thin a sample to use (according to conventional rules). But the real problem wasn't that there were only 5-10 late 20th century cores- there must have been a lot more. They were only using a subset of 10 cores as of 1990, but there was no reason to use a small subset. (Had these been randomly selected, this would be a thin sample, but perhaps passable. But it appears that they weren't randomly selected.)

http://www.climateaudit.org/?p=7142

8. Faced with a sample in the Taymir chronology that likely had 3-4 times as many series as the Yamal chronology, Briffa added in data from other researchers' samples taken at the Avam site, some 400 km away. He also used data from the Schweingruber sampling program circa 1990, also taken about 400 km from Taymir. Regardless of the merits or otherwise of pooling samples from such disparate locations, this establishes a precedent where Briffa added a Schweingruber site to provide additional samples. This, incidentally, ramped up the hockey-stickness of the (now Avam-) Taymir chronology.

http://www.climateaudit.org/?p=7158

9. Steve thus looked for data from other samples at or near the Yamal site that could have been used to increase the sample size in the Briffa Yamal chronology. He quickly discovered a large set of 34 Schweingruber samples from living trees. Using these instead of the 12 trees in the Briffa (CRU) group that extend to the present yields Figure 2, showing a complete divergence in the 20th century. Thus the Schweingruber data completely contradicts the CRU series. Bear in mind the close collaboration of Schweingruber and Briffa all this time, and their habit of using one another's data as needed.

10. Combining the CRU and Schweingruber data yields the green line in the 3rd figure above. While it doesn't go down at the end, neither does it go up, and it yields a medieval era warmer than the present, on the standard interpretation. Thus the key ingredient in a lot of the studies that have been invoked to support the Hockey Stick, namely the Briffa Yamal series (red line above) depends on the influence of a thin subsample of post-1990 chronologies and the exclusion of the (much larger) collection of readily-available Schweingruber data for the same area.

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rcschronologiesrev2.gif

The red line represents a sample of 12 tree ring cores from the CRU Archive. The black line a sample of 34 - from the same region. The sample of 34 was not included in the archive.

Any warministas out there still plan to invest in cherry tree orchards?

Thanks for that AFT, another nail in the hockey stick coffin. Point 10 confirms what most reasonable people think, that the MWP was warmer than now. Off course there are some who don't want to believe, for all of those the hockey stick lives on!fool.gif

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Meet the Global Warming tree.

YAD061

briffasingletreeyad061.png

Of the aforementioned 12 tree ring cores a single tree is responsible for virtually all of the recent warming trend.

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What I want to know is how do they isolate temperature from the rings? Tree growth is governed by many things, water, light, soil fertility etc, so how do they look at growth rings and decide retrospectively that it was warmth which made that year, a good year?

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That's a good question. It's not called a 'proxy' for nothing. It's an indirect guide to past temperature which is not just affected by temperature but by water, light, carbon dioxide and more.

In an Arctic zone I'd thought cloudiness would have a proportionately greater influence on tree growth than cloudiness would in a temperate zone like the UK.

In UK even in cloudy summers it is going to be mild enough for near optimum tree growth. But on the North Russian Arctic coast in the 'good' Arctic summers it's still going to be relatively cool and dry for a lot of the time.

Light may account for a greater proportion of a tree's growth the further north you go, so you may get false positives and negatives...?

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Someone provides a discussion on a rebuttal from a respected scientist, and why he disagrees, here:

http://www.di2.nu/200910/01a.htm

I would advise some scepticism regarding possible bias though as for instance his response to this:

My colleagues and I are working to develop methods that are capable of expressing robust evidence of climate changes using tree-ring data. We do not select tree-core samples based on comparison with climate data. Chronologies are constructed independently and are subsequently compared with climate data to measure the association and quantify the reliability of using the tree-ring data as a proxy for temperature variations.

emphatically does not yield this conclusion:

This paragraph in itself seems to hint at the problem. Briffa has to assume that tree ring chronologies are proxies for climate change because if it turns out they aren't he's out of funding.

When I read something like that, it screams "bias". Hopefully we will get a range of sources debating this shortly, as I would be quite interested to see the reliability of tree rings at measuring past climate change be questioned and evidence/analysis appear to add evidence for and/or against.

Regarding the posts by AFT and SC, I sense a strong element of confirmation bias regarding the assertions that McIntyre's work somehow makes him automatically right and Briffa et al. wrong. I am all in favour of questioning and analysing aspects of the scientific consensus but when bias and agendas are involved, as is regrettably the case with McIntyre, it makes for a rather uglier situation.

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McIntyre has invited Briffa and/or any colleagues to open a thread without any editorial control from him. Credit where credit's due, he may criticise and question the validity of studies but he gives a right of reply to those involved. Can't really be fairer than that IMO.

Here's Briffa's initial response: http://www.cru.uea.ac.uk/cru/people/briffa/yamal2000/

And McIntyre's response to that: http://www.climateaudit.org/

I'm sure this will run and run for quite some time, having done some digging around this morning to try and answer my queries about isolating the temperature signal, it appears there are methods but it's not a particularly reliable proxy to use; rainfall variation appears to have the greatest impact upon growth.

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To add a bit of even-handedness to my latest post, the person in the previous link I posted did make a good point near the end:

I do not believe that McIntyre's preliminary post provides sufficient evidence to doubt the reality of unusually high summer temperatures in the last decades of the 20th century.
Its good to know that treemometer mining continues apace. Unfortunately the final sentence seems to miss the point - possibly deliberately. Steve is not questioning whether recent summers were hotter than in the past he is questioning whether tree rings are a robust and reliable proxy for temperatures.

Oops...

On this particular topic, I get a feeling that Steve McIntyre might be onto something here. I've also noted the Climateaudit response with interest. It will be interesting to see how this progresses.

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I have to admit I've never been a great fan of tree ring proxies, I think combined with other proxies they can help to paint a picture of past climate, but the sample size needs to be large and it needs to be none regional.

Now on to the subject matter.

We all agree that science needs to be robust and capable of defending itself. It also needs to be critically but fairly examined.

IMO this work by Steve McIntyre is not about improving science it's about bitter personal attack this is true with Antony watts as well. I won't pull my punches when I describe both of them as calculated bullies that smear and attack science gladly, almost modern day thugs.

Steve knows full well that what he has done is a load of tosh, you only need to see the graph is has produced, where according to his workings temperatures are currently only marginally above the little ice age...um that doesn't seem right to me.

Has Steve attempted to contact Biffa as to why only a sub-sets of the cores where used.? No instead he's gone straight on the internet and attacked him personally, called him a deliberate liar and manipulator.

So even if Steve is right what does this tell us.

That the hockey stick is wrong.?, no not at all the only part of the reconstruction that he's disputing is the last 100 years and there is plenty of data to suggest that temperatures now are a lot higher than they were 100 years ago.

That Global temps are somehow lower now than they were previously ?. (again not at all this is tiny study in Russia and even if he was right would only show what happened in that one area of russia).

The only thing that Steve is trying to do is discredit a scientist (not that Steve is a scientist).

Are tree rings a reliable proxy by themselves, no not at all but I am not sure that anybody even Biffa is saying this.

Should tree rings be used to try and estimate current day temperatures, no not at all.

Is this a storm is a tea cup, caused by somebody deliberaltely stiring yes.

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Iceberg, with the greatest of respect I think you need to look at this again and perhaps reconsider a bit?

The information for this data set has been requested by many people for many years, Briffa has refused all requests; it is only now available because the Royal Society has insisted and enforced it's rule of archive.

At no point has McIntyre called anyone a deliberate liar. He has invited Briffa and his associates to openly comment upon both their work and his interpretation and criticisms of it.

How can that be so wrong?

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The information for this data set has been requested by many people for many years, Briffa has refused all requests; it is only now available because the Royal Society has insisted and enforced it's rule of archive.

Jethro, up until September 09 nobody knew global warming rested on just 12 trees (and out of that twelve, one in particular). Twelve, which from about 1995 became five trees.

Briffa had not made it clear to the Royal Soc. that his study was based on a miniscule sample size. Had it been known it would have been laughed from the editorial office. As it is it forms one of the increasingly pathetic looking planks of AGW.

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I have to admit I've never been a great fan of tree ring proxies, I think combined with other proxies they can help to paint a picture of past climate, but the sample size needs to be large and it needs to be none regional.

Now on to the subject matter.

We all agree that science needs to be robust and capable of defending itself. It also needs to be critically but fairly examined.

IMO this work by Steve McIntyre is not about improving science it's about bitter personal attack this is true with Antony watts as well. I won't pull my punches when I describe both of them as calculated bullies that smear and attack science gladly, almost modern day thugs.

Steve knows full well that what he has done is a load of tosh, you only need to see the graph is has produced, where according to his workings temperatures are currently only marginally above the little ice age...um that doesn't seem right to me.

Has Steve attempted to contact Biffa as to why only a sub-sets of the cores where used.? No instead he's gone straight on the internet and attacked him personally, called him a deliberate liar and manipulator.

So even if Steve is right what does this tell us.

That the hockey stick is wrong.?, no not at all the only part of the reconstruction that he's disputing is the last 100 years and there is plenty of data to suggest that temperatures now are a lot higher than they were 100 years ago.

That Global temps are somehow lower now than they were previously ?. (again not at all this is tiny study in Russia and even if he was right would only show what happened in that one area of russia).

The only thing that Steve is trying to do is discredit a scientist (not that Steve is a scientist).

Are tree rings a reliable proxy by themselves, no not at all but I am not sure that anybody even Biffa is saying this.

Should tree rings be used to try and estimate current day temperatures, no not at all.

Is this a storm is a tea cup, caused by somebody deliberaltely stiring yes.

Try telling that to the Royal society, they asked for this data numerous times.

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But the problem is in this current environment the data is released, then because somebody doesn't understand it and all the reasoning behind it(nor the science involved), it gets immediately vilified on the internet, picked up and blown out of proportion by the likes of Watts. Before they have a chance to respond (and by the way, neither watts nor McIntyre gave Biffa the chance to respond before posting it all over the internet) your names mud.

Is really how we want to conduct science, who's to say the Royal society didn't know the sample size, who's to say the experts who peer reviewed the paper didn't look at the raw data(I would be amazed if they didn't) ask these questions and then get sufficently good answers.?

Biffa, like Mann and lots of other scientists have been found guilty, hung and discredited on a tiny piece of the facts.

But regardless to this. To all the people saying that this discredits the hockey stick a simple question.

What percentage of the hockey stick relied on this one subset of data from Russia ?. I have a some knowledge of what it's likely to be. but do those judging and making such comments. ?

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That ignores the point- there are plenty of other sources of evidence for this controversial "hockey stick" including ice cores and the like. Tree rings are only one source of evidence and if tree rings are discounted (and I think McIntyre looks like he has a decent case here) it is only discounting one line of evidence.

If one line of evidence that discounted the hockey stick was shown to be faulty, would that mean that the hockey stick was true? I'm pretty sure that all of us would recognise the answer to that as "no", so why is it supposedly not the same when we're talking evidence supporting the hockey stick?

I have mixed views on McIntyre's behaviour, I think the questioning of data supporting AGW and the like is to be applauded, but some aspects of the way he is doing it are quite ugly I'm afraid. There is a sense of trying to discredit climate scientists as part of undermining the case for AGW, as opposed to attempts to question the consensus in order to get closer to the truth.

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This would seem to be a good time to ask the question: what data went into producing the Hockey Stick graph - in total?

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I'll repost the links I put in the general discussion thread here, so those who don't want to understand a bit of science can actually go and do some easy research:

http://www.realclimate.org/index.php/archives/2009/09/hey-ya-mal/#more-1184

It's really important to stress that while the tone of the piece is quite (understandably) combative, the information contained within it is verifiable. The crucial point to the deniers (and I will use that word to describe a few posts above) is that AGW does not just depend on 12 specially selected trees. Rather, it depends on a multitude of independent lines of evidence (glaciers, borehole temps, instumental data, to name but a few), of which tree rings are only one. If you have an open enough mind, read that article carefully. You'll also be interested in this one:

http://www.realclimate.org/index.php/archives/2005/01/what-if-the-hockey-stick-were-wrong/

...the upshot of which is that it does not change our assessment of 20th century climate change. There are no 'nails in the coffin of AGW', because little or none of the mud hurled round the internet actually sticks to the data provided by thousands of independent scientists, independently producing the same results, at least not when you look at the data with an unclouded mind.

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Some good debates in the "comments" sections of those RealClimate articles- those are well worth a look as well as the main articles.

From the second article, this quote is quite important:

One would think that some things go without saying, but apparently people still get a key issue wrong so let us be extremely clear. Science is made up of people challenging assumptions and other peoples’ results with the overall desire of getting closer to the ‘truth’. There is nothing wrong with people putting together new chronologies of tree rings or testing the robustness of previous results to updated data or new methodologies. Or even thinking about what would happen if it was all wrong. What is objectionable is the conflation of technical criticism with unsupported, unjustified and unverified accusations of scientific misconduct. Steve McIntyre keeps insisting that he should be treated like a professional.

I think that article also makes it clear that if we are to prove the hockey stick wrong, we need to disprove a large range of different lines of evidence. If we succeed in disproving one, it won't be anywhere near enough on its own.

Regarding what may happen if the "hockey stick" turns out to be wrong- yes, even if the Medieval Warm Period was warmer than today it doesn't say much about the probability of anthropogenic forcings currently having a large influence. It would cast doubt upon the accuracy of some of the measurements and methodologies, but then again we already know that there is a fair amount of uncertainty surrounding the subject, and most scientists will readily admit to this.

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I'll repost the links I put in the general discussion thread here, so those who don't want to understand a bit of science can actually go and do some easy research:

http://www.realclimate.org/index.php/archives/2009/09/hey-ya-mal/#more-1184

It's really important to stress that while the tone of the piece is quite (understandably) combative, the information contained within it is verifiable. The crucial point to the deniers (and I will use that word to describe a few posts above) is that AGW does not just depend on 12 specially selected trees. Rather, it depends on a multitude of independent lines of evidence (glaciers, borehole temps, instumental data, to name but a few), of which tree rings are only one. If you have an open enough mind, read that article carefully. You'll also be interested in this one:

http://www.realclimate.org/index.php/archives/2005/01/what-if-the-hockey-stick-were-wrong/

...the upshot of which is that it does not change our assessment of 20th century climate change. There are no 'nails in the coffin of AGW', because little or none of the mud hurled round the internet actually sticks to the data provided by thousands of independent scientists, independently producing the same results, at least not when you look at the data with an unclouded mind.

I hope your not suggesting that I'm a denier, I've stated countless times I believe in AGW as a theory, just the magnitude I strongly dispute! And what you have posted provides nothing new, and I stand by what I stated regarding proxies. You posted this on the general climate thread, and had the cheek to say for all those with open minds!! It seems pretty obvious that your mind is made up, so why denounce others for being the same! :good:

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The flawed Bristlecone pines proxy was also a source for the curve in the hockey stick.

As are the data processing algorithms which Mann used to process his temperature data - they have been proven to throw out hockey stick shaped lines whether or not real temperature data or "red noise" is fed into it.

As were the ability to turn temperature datasets upside down and feed them into the model.

This has been the subject of McIntyre's earlier published work.

Nobody is saying there hasn't been any empirical evidence for warming in the late 20th Century. But there is no evidence for this warming being a "historic" hockey stick shape. It's just regular old warming, and there has recently been some cooling and there might be more.

There's no hockey stick. It's an irrelevance that believers in AGW should ditch as it does not help their cause. (Nor does a lack of hockey stick 100% kill their idea, but it certainly doesn't help it...)

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Some good debates in the "comments" sections of those RealClimate articles- those are well worth a look as well as the main articles.

From the second article, this quote is quite important:

I think that article also makes it clear that if we are to prove the hockey stick wrong, we need to disprove a large range of different lines of evidence. If we succeed in disproving one, it won't be anywhere near enough on its own.

Regarding what may happen if the "hockey stick" turns out to be wrong- yes, even if the Medieval Warm Period was warmer than today it doesn't say much about the probability of anthropogenic forcings currently having a large influence. It would cast doubt upon the accuracy of some of the measurements and methodologies, but then again we already know that there is a fair amount of uncertainty surrounding the subject, and most scientists will readily admit to this.

It cast doubt on the honesty, and integrity of climate scientist. The hockey stick was the flagship, that proved we was warmer now than the MWP. And it was the IPCC, who held it up as some sort of holy grail of science. I'm so sorry if I find that offensive, but truth and integrity is something I hold dear to my heart!

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Can either of you two answer my question about the importance of the Russian tree core samples in the Hockey Stick, since you are so determined to have a kick at it ?.

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Can either of you two answer my question about the importance of the Russian tree core samples in the Hockey Stick, since you are so determined to have a kick at it ?.

I don't think you'll get a straight answer - that would involve dealing with real data...

AS TWS has commented, and is the focus of the first of the RealClimate articles, the hockey stick, and most importantly, the late 20th century rise, appears in a plethora of different records and will not disappear because of an internet character assassination job on one tree ring record. It still stands, despite the rantings of people like McIntyre or, god forbid, Crichton (should have stuck to the story writing he was actually good at, rest his soul), who are not capable of putting together a climate argument cogent enough to get published. Unsubstantiuated blog opinions like those of Watts do not qualify as cogent criticisms of recent climate change or the 'hockey stick' either. That people on here believe such unsubstantiated arguments and are so opposed to taking on board views (including those of most trained palaeoclimatologists) contrary to their own is frankly depressing.

I would strongly encourage everyone to read both sides of the argument, but avoid the rhetoric, and look carefully for the real, verifiable data. It is particularly telling that deniers spend their time nit-picking holes in individual records, the nit-picks themselves don't then stand up to examination, and no new data clearly supporting alternate hypotheses are put forward. The most depressing thing of all is that the internet becomes the vehicle for unsubstantiated character assasination attempts, where the author who has suceeded in publishing work in journals and therefore survived the academic review process, has no opportunity or means to defend themselves. The rumours spread like viruses around the web for the uninformed and weak-minded to read, and even the less rigorous/scrupulous journalists see a story. Strangely enough, the rebuttals of the 'critiques' rarely make such a media-worthy story and so many people are left with the (wrong) opinion on the state of the science.

I'm happy to discuss reasoned arguments, but not to discuss unsubstantiated slander of honest scientists. I want to be wrong about all this. I want iot to get cooler, and for the current solar inactivity to spark a new 'Little Ice Age'. I've even given talks about the sun's connection to climate some years ago, but the trouble is the data is very clear, and so yes, SC, my mind is made up... until new, better evidence comes forward, which do date it resoundingly hasn't. There is an excellent test of some ideas given the current deep solar minimum and negative PDO, but so far no discernible impact on temperature.

SC: "It cast doubt on the honesty, and integrity of climate scientist." Erm, no it doesn't. The scientists in question are quite happy to be proved wrong if new, better data comes along, but if they are proven wrong they are no less honest as scientists than they were before. That is the core of the scientific method, or do you not believe that either? Dishonesty is the deliberate falsification of results, something that hasn't happened. A very serious accusation, levelled apparently by you at nearly all palaeoclimatologists.

AF: "Nobody is saying there hasn't been any empirical evidence for warming in the late 20th Century. But there is no evidence for this warming being a "historic" hockey stick shape. It's just regular old warming, and there has recently been some cooling and there might be more. There's no hockey stick. It's an irrelevance that believers in AGW should ditch as it does not help their cause. (Nor does a lack of hockey stick 100% kill their idea, but it certainly doesn't help it...)". Erm... yes there are plenty independent lines of evidence - see the first of the links in my previous post. And temperatures are still rising on average.

SC, I did not specifcally call you a denier. But... if you're going to deny that palaeoclimate science in all it's myriad independently verifiable forms can reconstruct past climate (to varying levels of accuracy and resolution), then it will be very hard to have a cogent debate!

AF: You might want to retract the comment: "up until September 09 nobody knew global warming rested on just 12 trees (and out of that twelve, one in particular). Twelve, which from about 1995 became five trees." If you seriously believe this then you have absolutely not read any of the literature on the topic, and are not in a position to comment. It is comments like these that mislead those who have no prior knowledge of the topic.

sss

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Iceberg, your question has already been answered at climate audit. I provided a brief summary for you above (did you read it?). You should start reading it from the source.

When you consider the hockey stick shape requires the recent period to be higher than the MWP the curve is going to depend on treemometers. The curve can be entirely explained by two: Mann's Bristlecone pines (and Mann's hockey stick algorithm) and Briffa's supposedly independent confirmation of this, the Global Warming tree.

Climate Audit for the source.

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